1. Field of the Invention
The present invention relates generally to implantable cardiac stimulators having one or more associated electrical leads that are insertable into an electrical connector in the cardiac stimulator, and relates more particularly to a tool for assisting in the insertion of the lead and for ensuring that the lead is fully inserted into the connector.
2. Background Information
Implantable cardiac stimulators generally include signal sensing, telemetry, and electrical stimulus generating circuitry, as well as a battery and other components that are hermetically sealed within a metal housing or "can." At least one electrically conducting lead having one or more electrodes designed for endovascular insertion within one or more chambers of the heart is provided externally of the metal housing. Typically, electrical connection between the circuit located within the can and the external electrically conducting lead is accomplished via a connectable and disconnectable electrical connector. The female portion of the connector, sometimes known as a connector block, is often embedded within a nonconducting transparent epoxy header attached to the outside of the metal housing. The connector block communicates with the exterior of the header via a passageway molded within the header. The connector block is electrically connected to the circuitry located within the metal housing via hermetic insulated feedthroughs located in the wall of the metal housing and extending into the epoxy header. The male portion of the connector, sometimes known as a connector pin, is attached to a proximal end of the lead and is configured to be received through the molded passageway into the connector block. Mechanical and electrical connection between the connector pin and the connector block is assured by a set screw in the connector block.
During implantation of the cardiac stimulator in a patient, the distal end of the lead including the electrodes is first implanted via an endovascular route into the interior of the heart. The cardiac stimulator is then implanted in a subcutaneous pocket and the proximal end of the lead is connected to the header of the cardiac stimulator. During insertion of the connector pin of the lead into the connector block of the cardiac stimulator, the physician usually looks into the transparent header to observe the progress of the connector pin, and can visually verify that the connector pin of the lead has been fully inserted into the connector block.
It has been suggested that implantable cardiac stimulators could be made smaller and more compact if the epoxy header were eliminated and the female portion of the connector were contained within the metal housing, with the connector being hermetically separated from the remainder of the interior of the metal housing. Such an arrangement might be described as a "headerless" cardiac stimulator. Because the metal housing is opaque, insertion of the connector pin of the lead within the cardiac stimulator connector could not be visually verified in such a headerless cardiac stimulator. Thus, the adoption of a headerless configuration for a cardiac stimulator would give rise to a need for a way to ensure that the connector pin of the lead is fully inserted. The present invention addresses and fulfills that need.